Sometimes clients do believe they're in the "production" environment, which is usually called "prod" around here. After one of them sent a report to the foreman, the environment becomes sticky: puppet:import:puppet_classes tries but doesn't remove the environment as there're still hosts in it.

Either the task should recognise the futility and avoid trying to remove the environment, or it should be forceful enough to actually do so. The first option is less destructive. A log entry might help pointing to a fishy configuration, but also might be annoying if the brokenness of the environments is already known.